The present disclosure relates to a light source device.
Japanese unexamined patent application No. 2011-233511 describes a vehicular head lamp 90 having a configuration including a semiconductor laser 91, an optical fiber 92, and light-emitting part 93 including a fluorescent material, as shown in FIG. 12. Light of the semiconductor laser 91 passes through the optical fiber 92 and irradiates the light emitting part 93. The optical fiber 92 has a two-layer structure of a core and a cladding that covers the core, in which the cladding has a refractive index smaller than that of the core. The core is primarily made of quartz glass, and the cladding is primarily made of quartz glass or a synthetic resin with a refractive index smaller than that of the core.